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Erschienen in:

01.05.2012 | Computed Tomography

Spectral Hounsfield units: a new radiological concept

verfasst von: Michael Anthony Hurrell, Anthony Philip Howard Butler, Nicholas James Cook, Philip Howard Butler, J. Paul Ronaldson, Rafidah Zainon

Erschienen in: European Radiology | Ausgabe 5/2012

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Abstract

Objective

Computed tomography (CT) uses radiographical density to depict different materials; although different elements have different absorption fingerprints across the range of diagnostic X-ray energies, this spectral absorption information is lost in conventional CT. The recent development of dual energy CT (DECT) allows extraction of this information to a useful but limited extent. However, the advent of new photon counting chips that have energy resolution capabilities has put multi-energy or spectral CT (SCT) on the clinical horizon.

Methods

This paper uses a prototype SCT system to demonstrate how CT density measurements vary with kilovoltage.

Results

While radiologists learn about linear attenuation curves during radiology training, they do not usually need a detailed understanding of this phenomenon in their clinical practice. However SCT requires a paradigm shift in how radiologists think about CT density.

Conclusion

Because radiologists are already familiar with the Hounsfield Unit (HU), it is proposed that a modified HU be used that includes the mean energy used to obtain the image, as a conceptual bridge between conventional CT and SCT. A suggested format would be: HU_keV.

Key Points

• Spectral computed tomography uses K-edge and slope effects to identify element signatures.

• New visualisation tools will be required to efficiently display spectral CT information.

• This paper demonstrates HU variation with keV using the Medipix3 chip.

• HU _keV is a suggested format when stating spectral HU measurements.

A joint project between the CERN Medipix2 Collaboration, Geneva, and the University of Canterbury, New Zealand.

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Titel: Spectral Hounsfield units: a new radiological concept
verfasst von: Michael Anthony Hurrell
Anthony Philip Howard Butler
Nicholas James Cook
Philip Howard Butler
J. Paul Ronaldson
Rafidah Zainon
Publikationsdatum: 01.05.2012
Verlag: Springer-Verlag
Erschienen in: European Radiology / Ausgabe 5/2012
Print ISSN: 0938-7994
Elektronische ISSN: 1432-1084
DOI: https://doi.org/10.1007/s00330-011-2348-3

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Spectral Hounsfield units: a new radiological concept